Liner assembly for ore grinding mill

ABSTRACT

The present invention provides a system and method for more efficient utilization of comminution mills. Sensors are provided in the liners placed within the mill shell. The sensors may include RFID tags, liner wear profile sensors (e.g., such as an ultrasonic sensor), an inertial sensor (preferably included both an inclinometer and an accelerometer, and an acoustic sensor, among others. When the liners are installed in the shell, the RFID tag is used to register the location of the liner within the shell. In operation, the information provided by the sensors is collected by a data transmission unit and sent by transmitter over the air to a computer having an antenna and receiver for such data. The data is correlated and the data is reviewable in real time while the mill is in running.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. Pat. Application No.16/443,388, claims the benefit of U.S. Provisional Pat. ApplicationSerial No. 62/686,649, filed on Jun. 18, 2018, the disclosure of whichis incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to mining, more particularly toore grinding and milling machines, and still more particularly to asystem and method for more efficient utilization of comminution mills.

BACKGROUND OF THE INVENTION

Comminution mills are large rotating drums for reducing ore to a usableform. Ore, or “media,” tumbles within the drum as it rotates, fallingupon itself, impacting the inner surfaces of the mill, and impactingmill charge, which often includes loose metal balls or rods inside themill. This process cuts, crushes, and grinds large ore into small ore,or small ore into fine powder.

The milling process is quite old but works well. Interactions betweenthe media, the charge, and the inner surfaces can quickly reduce ore toa manageable and usable form, depending on the application. Notsurprisingly, this process is incredibly destructive on the machinery.As a result, mills are always fit with liners. Were mills not protectedwith liners, the media and charge would directly impact the shell of themill, would wear a hole through the shell, and the entire mill would behave to be replaced. The use of liners protects the shell. Accordingly,instead of the mill wearing out, the liners are worn as the milloperates.

Eventually the liners must be replaced. However, downtime of a day ortwo during re-line can represent potentially tens if not hundreds ofthousands of dollars in lost opportunity. Mill operators thus prefer toperform re-lines as infrequently and as quickly as possible. But theymust perform repair work every time a liner becomes damaged to the pointwhere it jeopardizes the safety or integrity of the mill. So milloperators sometimes replace liners or perform re-lines too soon. When anentire crew is performing a re-line, it can be more efficient to replacepartially worn liners that still have usable life in them than to bringthe crew back later and put the mill out of commission a second time.Premature or unnecessary replacement has costs, too, of course.

Therefore, there arises a need in the art for a system and method tomonitor liners, schedule re-lines, and improve efficiency of comminutionmills.

SUMMARY

The present invention discloses a system and method for more efficientutilization of comminution mills. One or more sensors are provided inthe liners placed within the mill shell. The sensors may include RFIDtags, liner wear profile sensors (e.g., such as an ultrasonic sensor),an inertial sensor (preferably included both an inclinometer and anaccelerometer, and an acoustic sensor, among others. When the liners areinstalled in the shell the RFID tag is used to register the location ofthe liner within the shell.

In operation, the information provided by the sensors is collected by adata transmission unit and sent by transmitter over the air to acomputer having an antenna and receiver for such data. The computer’sCPU takes the data and updates a database using the RFID information tocorrelate the received information to the respective liner. An operatoris able to review the data in real time while the mill is in running todetermine the efficiency of the mill and to determine if the any of theliners require replacement. Changes may be made to the operation of themill based on this information.

Therefore, according to one aspect of the invention, there is provided aliner assembly, of the type utilized as a wear item in the interior of acomminution mill from the media and charge, comprising: a body having alength, width, and depth, the body located within the comminution milland further having a void formed in a portion of the body; and a sensorlocated in the void in the body, the sensor arranged and configured tomeasure a change in the depth of the body.

Further to the above paragraph, additional aspects include (alone or incombination): wherein the sensor is an ultrasonic sensor; furtherincluding an acoustic sensor for generating a signal indicative of thenumber of strikes on the liner assembly from the media and charge duringoperation of the comminution mill; further including an accelerometersensor for generating a signal indicative of the intensity of strikes onthe liner assembly from the media and charge during operation of thecomminution mill; further including an accelerometer sensor forgenerating a signal indicative of the relative position of the linerassembly within the comminution mill during operation of the comminutionmill; and wherein the liner assembly further includes an RFID tag,whereby the location of the liner assembly within the comminution millmay be registered upon installation of the liner assembly within themill.

According to second aspect of the invention, there is provided a systemfor monitoring the operation of a comminution mill, comprising: aplurality of liner assemblies, the liner assemblies located within thecomminution mill in a known position; a plurality of sensors to monitora wear parameter of the liner assemblies, wherein each liner assemblyincludes a corresponding sensor, each sensor is arranged and configuredto generate a first signal indicative of a wear parameter of thecorresponding liner assembly, and each sensor is located at leastpartially within the corresponding liner assembly; and a plurality oftransmitters, the plurality of transmitters transmitting the firstsignals for comparison to predetermined wear reference values.

According to yet another aspect of the invention, there is provided amethod for determining the timing for replacement of a liner assemblywithin a comminution mill, comprising: placing a sensor for measuring awear profile within a liner assembly; registering the position of theliner assembly within the comminution mill, whereby position of thesensor within the comminution mill is also known; and monitoring theoutput of the sensor to determine an appropriate time to replace theliner assembly based on the wear profile.

While the invention will be described with respect to preferredembodiment configurations, methods and specifications, it will beunderstood that the invention is not to be construed as limited in anymanner by either such configuration, methods and/or specificationsdescribed herein. Further, while the various sensors are described asspecific types of sensors herein and are shown in specific locationswithin the liners, the principles of this invention extend to utilizingsensors located within the drum (i.e., within the shell of thecomminution mill). These and other variations of the inventions willbecome apparent to those skilled in the art upon a more detaileddescription.

The advantages and features which characterize the inventions arepointed out with particularity in the claims annexed hereto and forminga part hereof. For a better understanding of the inventions, however,reference should be had to the drawings which form a part hereof and tothe accompanying descriptive matter, in which there is illustrated anddescribed embodiments of the inventions.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the drawings wherein like numerals represent like partsthroughout the several views:

FIG. 1 is a partial section view of a mill outfitted with improved linerassemblies;

FIG. 2 is an enlarged partial section view showing two liner assembliesinstalled on the shell of the mill;

FIGS. 3A-3D are bottom perspective, top plan, side elevation, and bottomplan views of a liner assembly, respectively;

FIG. 4 is a section view through a liner assembly;

FIG. 5 is a top perspective view of a data transmission unit for use inthe liner assembly;

FIG. 6 is a section view through a liner assembly installed in the shellof the mill; and

FIG. 7 is a side elevation view of a liner assembly installed in theshell of the mill.

FIG. 8 is a schematic functional block diagram of the system utilized inconnection with the various sensors installed in the liner assembly.

FIG. 9 is an illustration of the method steps which may be used topractice the principles of the present invention.

DETAILED DESCRIPTION

Reference now is made to the drawings, in which the same referencecharacters are used throughout the different figures to designate thesame elements. FIG. 1 is a partial section view of an ore grinding mill11 fitted with a plurality of liner assemblies 10. The liner assemblies10 protect a shell 12 of the mill 11 during operation of the mill 11,when it is comminuting ore. The liner assemblies 10 are arranged alongthe inner surface of a cylindrical sidewall 13 of the shell 12 and alsoon the inner surface of opposed endwalls 14 and 15. The liner assemblies10 mounted on the sidewall 13 are different in shape and arrangementfrom the liner assemblies 10 on the endwalls 14 and 15 but have theinventive features and elements described herein. As such, thedescription herein refers only to the liner assemblies 10 on thecylindrical sidewall 13 with the understanding that it applies equallyto the liner assemblies on the endwalls 14 and 15.

FIG. 2 shows in greater detail two liner assemblies 10 mounted to theshell 12. Only one liner assembly 10 will be referred to herein. Theliner assembly 10 has a body 16 including a central crown 17 and opposedside flanges 18. The body 16 is elongate, and the crown 17 and flanges18 extend along the length of the body 16. The crown 17 projectsupwardly from the flanges 18 and is a prominent impact site for the oreas it tumbles within the mill 11. The crown 17 has two angled impactsurfaces which extend obliquely down to the flanges 18.

The liner assembly 10 is mounted to the shell 12 with a plurality ofbolts 20. The bolts 20 are passed through bores 21 in the shell 12 andsecured with nuts 22 on the outside of the shell 12, where each nut 22can be accessed and tightened and loosened on a particular bolt 20. Thebolts 20 have enlarged heads which are seated in bores 23 in one of theflanges 18 of the liner assembly 10 to hold the liner assembly 10tightly and securely to the shell 12. The bores 21 are pre-formedthrough the shell 12 by the manufacturer of the mill 11, and the bores23 in the liner assembly 10 are formed to register with those bores 21.However, not all of the bores 21 in the shell 12 correspond to the bores23 in the liner assembly 10. Instead, at least one bore 21 under eachliner assembly 10 is occupied by a data transmission unit (“DTU”) 30.The DTU 30 is connected to various data-gathering instruments on theliner assembly 10.

FIG. 3A illustrates the liner assembly 10 from “below,” showing theinner surface 31 which is concealed against the shell 12 when mountedthereon, and which is opposite the outer wear surface 32 exposed to themilling charge and ore. Several depressions are formed inward into theliner assembly 10 from the inner surface 31, defining cavities 33 in theliner assembly 10. The data-gathering instruments are preferably mountedin these cavities 33.

As seen in FIG. 3D, within an H-shaped cavity 33 are disposed aninertial sensor 40, an acoustic sensor 41, and two ultrasonic sensors 42and 43. Each of these sensors 40-43 is coupled in wired datacommunication with the DTU 30. The sensors 40-43 gather informationabout the operation of the mill 11, the conditions of the charge andmedia, and the conditions of the liner assembly 10 itself.

The inertial sensor 40 includes both an accelerometer and aninclinometer. When connected through the DTU 30 to a computer (describedin more detail below), the inertial sensor 40 provides information aboutthe movement of the mill 11. The inertial sensor 40 records data aboutrotational acceleration and velocity of the mill 11. The inclinometerprovides information about the angle of the liner assembly 10, fromwhich a computer can determine the position of the liner assembly 10 inthe mill 11. In other words, based on the incline of the inertial sensor40, the computer can determine, for example, if the liner assembly hasrotated around to the bottom of the mill 11, is at the top of the mill11, or is somewhere therebetween. The computer can thus determine theorientation of the crown 17 and the wear surfaces of the crown 17.

The acoustic sensor 41 records information about impacts on the wearsurface 32 of the liner assembly 10. The acoustic sensor 41 can measurethe number, frequency, and intensity of impacts of charge and mediaagainst the liner assembly 10. The intensity of the impacts correspondsto the proportion of charge and media impacting the liner assembly 10,and so the operator can determine how much ore is hitting the linerassembly 10 versus milling charge. Impacts of different proportions ofmedia and charge have different comminution efficiencies, and so knowingthe type of impact occurring within the mill 11 is useful in analyzingwhether the impacts are effectively reducing the ore. Moreover, theintensity of the impact also corresponds to the context of the impact,namely, whether the mix of media and charge is falling upon itself or isfalling upon exposed wear surfaces of the liner assemblies 10. This,too, affects both the efficiency of the comminution and the wear on theliner assemblies 10. By combining this data with that gathered from theinertial sensor 40, a mill operator can determine how the rotationalspeed of the mill 11 affects the efficiency of the communication and thewear on the liner assemblies 10. The operator can then adjust the speedof the mill 11 to make milling more or less efficient, faster or slower,hotter or cooler, etc.

The ultrasonic sensors 42 and 43 are shown in FIG. 3D but also in FIG. 4. The sensors 42 and 43 are mounted within small sockets or seats 44 setin from the cavity 33. One ultrasonic sensor 43 is mounted under thecrown 17 and the other is mounted under the flange 18. The ultrasonicsensors 42 and 43 transmit ultrasonic waves within the body of the linerassembly 10. The waves bounce within the body and some return to thesensors 42 and 43 where they are received. The sensors 42 and 43 collectthis data and transmit it to the DTU 30. A computer connected to the DTU30 can interpret the data to determine whether and how far the wearsurface 32 of the liner assembly 10 is worn or damaged. When a thresholdlevel of wear is detected, the mill operator instructs the linerassembly 10 to be replaced.

When replacement is necessary, the mill operator can easily identify theliner assembly 10. As seen in FIG. 3A, the liner assembly 10 includes anRFID tag 45. The RFID tag 45 is attached to the end of the linerassembly 10 and is coupled in wireless data transmission to the DTU 30.The RFID tag 45 is programmed with identification information when thebody 16 of the liner assembly 10 is molded and is affixed to the body 16just after the body 16 is heat treated. The RFID tag 45 thus is used foridentification of the liner assembly 10 not just during the operatinglife of the liner assembly 10, but before and after as well. The foundrywhich creates the body 16 of the liner assembly 10 tracks its movementthrough the foundry grounds with the RFID tag 45, tracks application ofthe DTU 30 and the sensors 40-43 to the body 16, and tracks the linerassembly 10 through shipping and delivery. When the liner assembly 10 isapplied to the mill 11 during initial construction or a re-line, thedate and time of installation are recorded and associated with the RFIDtag 45, so that the precise operating life of the liner assembly 10 isknown. In this way, automatic and electronic records can be maintainedfor each liner assembly 10 throughout its lifecycle. When the linerassembly 10 needs to be removed, it can be quickly located with the RFIDtag 45.

The DTU 30 on each liner assembly 10 provides the communication betweenthe sensors 40-43, the RFID tag 45, and the mill operator’s computer.FIG. 5 shows the DTU 30 in detail. The DTU 30 includes a rugged housing50 with a narrowed post 51. The housing 50 contains a stored powersource such as a battery and a programmable controller coupled to an LCDdisplay 52 carried on a head end of the DTU 30 for displayinginformation relating to the DTU 30 and to the sensors 40-43. Thecontroller within the housing 50 is coupled to the sensors 40-43 with aconnector cable 53 extending from the end of the post 51. As seen inFIG. 6 , the cable 53 runs through the cavity 33 from the post 51 to thesensors 40-43. The second view of FIG. 6 shows the cable 53 connectingonly the ultrasonic sensor 43, but FIG. 3D shows the cable 53 connectedto all the sensors 40-43. Thus, there is a physical, wired connectionbetween the DTU 30 and the sensors 40-43, whereas there is a wirelessconnection between the DTU 30 and the RFID tag 45.

FIGS. 6 and 7 also show how the DTU 30 is mounted in the shell 12.Rather than being buried in the liner assembly 10, the DTU 30 is setinto a bore 21. The post 51 is snug fit into the bore 21 and is securedwith fasteners or bolts into the shell 12. To prevent the possibility ofslurry leakage through the bore 21, a gasket is compressed between thebore 21 and the DTU 30. The length of the post 51 is approximately equalto the thickness of the shell 12, and the post 51 extends through theshell 12 in the bore 21 to the cavity 33. This arranges the head end ofthe DTU 30 outside the shell 12, so that the display 52 can be observed.The head end further has an antenna 54. The antenna 54 couples the DTU30 to a wireless data network, so that the mill operator’s computer canconnect with the DTU 30, the sensors 40-43, and the RFID tag 45.

Turning now to FIG. 8 a functional block diagram is illustrated of anembodiment in accordance with the principles of the present invention.The shell of the mill is illustrated in dashed line at 800. Included inshell 800 is the mill cylindrical shell 12 and the mill conical heads atthe feed end and the discharge end. The plurality of liner assemblies801 a, 801 b, 801 c. . . 801 n may each be arranged and configured inaccordance with the description of liner assembly 12 above. Further,each respective liner assembly 801 a - 801 n preferably includes atleast one corresponding sensor 802 a, 802 b, 802 c... 802 n and acorresponding transmitter 803 a, 803 b, 803 c. . . 803 n.

In one embodiment, each of the liner assemblies 801 a-801 n includes aplurality of sensors, including an RFID sensor, an inclinometer, anacoustic sensor, an inertial sensor and an ultrasonic sensor. However,it will be appreciated that the number of sensors in each liner assembly801 a-801 n may vary. For example, in connection with the linerassemblies located on the mill conical heads, providing all of thesensors in each liner assembly may not be useful and/or required. Thus,the blocks 802 a - 802 n generally include from at least at least onesensor up to several sensors.

Representative examples of sensors which may be used in connectioninclude the following. The accelerometer (inertial sensor) is a 3-axiscommercial device available under model number ADXL337 manufactured byAnalog Devices of Norwood, Massachusetts. The acoustic sensor is a soundimpact sensor available under model number Parallax 29132 of Parallax,Inc. of Rocklin, California. One data transmitter which may be used aspart of the DTU is available commercially under the model numberdesignation Photon in Particle’s Internet of Things, San Francisco,California. Ultrasonic sensors for use as non-destructive testingthickness gauges are available commercially from many differentmanufacturers (e.g., Cygnus Instruments of Jacksonville, Florida).

A mill computer 806 is illustrated as including a receiver 807,processor or CPU 808, and memory 809. The computer may be a personalcomputer or a special purpose computer. A monitor and attendant userinterface devices, such as input devices (i.e., a mouse and keyboard)are shown at block 820. The mill computer 806 and user interface 820together comprise the mill performance evaluation block identified by805. For example, the data received from the sensors 802 a-802 n may becompiled into a spreadsheet in real time so that a user may review thedata at the mill performance block 805 and make adjustments to theoperation of the mill and/or to determine that one or more linerassemblies 801 a-801 n have become thin or otherwise worn, and need tobe replaced. A wear profile for the liner assemblies 801 a-801 n ispreferably determined such that the user is able to identify from thedata when a wear level is reached and replacement is desired for anyindividual liner 801 a-801 n. Further, the computer 806 is preferablyconnected to the mill operation block 814 so that a user may adjust theoperating parameters of the mill (i.e., such as mill speed and ore feedrate, among others) based on the data received from the various sensors802 a-802 n.

Antenna 810 receives the data from the plurality of transmitters 803a-803 n. The antenna is connected to receiver 807. The plurality ofover-the-air signals is identified by the arrow 815. To store the data,the computer 806 includes memory 809, as well as preferably beingconnected to cloud storage 812 and/or server 813.

Computer 806 is further connected to RFID sensor 811. The RFID sensor811 may be used to determine the location of the specific liner assembly801 by scanning an RFID tag on the liner assembly during theinstallation of the liner assembly within the mill 800. In this mannerthe location of the liner assembly and its corresponding sensors are ina known (or registered) location both within the mill 800 and in aposition relative to the other liner assemblies 801 a-801 n.

Next referring to FIG. 9 , a flow chart illustrating the logical stepswhich may be taken in operation is disclosed generally at 900. At block901, the liner assemblies 10 are installed within the mill. In the eventthat it is the initial installation of liner assemblies 10 in accordancewith the principles of the invention, then each of the liner assemblies10 will be installed and the specific position registered using an RFIDsensor 811 and added to a database, spreadsheet, or other informationpresentation array (referred to for convenience as “database”) incomputer 806. Thus, the RFID tag aids in identifying from which linerassembly 10 the data provided by the plurality of sensors 802 a-802 n iscoming. After initial installation, the comminution mill may beperiodically stopped for replacement of liner assemblies 10 that havereached the predetermined wear in thickness or other predetermined wearprofile. The replacement liner assemblies 10 also preferably include anRFID tag to aid in registering the location of the specific liner withinthe mill.

At block 902, the mill is operated and the sensors 802 a-802 n providedata to the respective DTU 30. At block 903, the DTUs 30 receive thedata from the sensors 802 a-802 n. The data may be stored in a temporaryfashion for batch transmission or may be transmitted in real-time. Ifbatch transmission is utilized, those of skill in the art will recognizethat a relatively shorter period of time between transmissions may bemore useful for an operator or user to review the sensed data via themill performance evaluation block 805. The data is transmitted from theDTUs 30 in a wireless fashion from transmitters 803 a-803 n to antenna810. At block 904, the CPU 808 moves the data from receiver 807 andupdates the database in memory 809. As data accumulates, the data may bestored in cloud storage 812 or on server 813. In addition, by moving thedata to one or both of these areas, remote viewing of the data isenabled.

At block 905, the updated database is provided to the operator via userinterface 820. Based on the data from the various sensors, the user maydetermine that a change in operation is desired or necessary. Further,the data may indicate the one or more liner assemblies 10 should bereplaced -e.g., either because a wear profile has been reached and/or asensor has stopped operating. Representative actions which may be takenby an operator reviewing the data are provided in the following Table 1.

TABLE 1 SENSOR USE IF THEN RFID Sensor RFID Tags are programmed withinformation When liner is installed -Triggers log event -Liner isentered into database Liner is removed -Triggers log event -Liner isupdated in database -Liner lifecycle is established Inertial Sensor(Inclinometer and accelerometer) -Works with acoustic sensor -Detectsangular location Large impacts are detected A) Mill speed decreases B)Ore feed rate increases Acoustic Detect impact of grinding media Largeimpacts are detected A) Mill speed decreases B) Ore feed rate increasesUltrasonic Transducer Monitor mill liner wear surface thickness Liner(s)become worn and/or reach a predetermined wear profile Liner(s) arechanged to protect the mill shell

As noted in the above Table 1, in the event that certain conditionsarise, then an action may be taken to increase the efficiency of theoperation of the mill. Further, the efficiency of keeping the mill inoperation until required replacement of liner assemblies 10 is alsomaximized.

An embodiment is fully and clearly described above so as to enable onehaving skill in the art to understand, make, and use the same. Thoseskilled in the art will recognize that modifications may be made to thedescription above without departing from the spirit of the invention,and that some embodiments include only those elements and featuresdescribed, or a subset thereof. To the extent that modifications do notdepart from the spirit of the invention, they are intended to beincluded within the scope thereof.

It should be understood that even though numerous characteristics andadvantages of the present invention have been set forth in the foregoingdescription, together with details of the structure and function of theinvention, the disclosure is illustrative only and changes may be madein detail, especially in matters of the supporting hardware, componentsand devices, and to the full extent indicated by the broad generalmeaning of the terms in which the appended claims are expressed.

What is claimed is:
 1. A method for determining the timing forreplacement of a liner assembly within a comminution mill, comprising:a) placing a sensor for measuring a wear profile within a linerassembly; b) registering the position of the liner assembly within thecomminution mill, whereby position of the sensor within the comminutionmill is also known; and c) monitoring the output of the sensor todetermine an appropriate time to replace the liner assembly based on thewear profile.
 2. The method of claim 17, wherein the sensor is anultrasonic sensor.
 3. The method of claim 18, further comprisingregistering the position of the liner assembly by including an RFID tagwith a unique identification information in the liner assembly.
 4. Themethod of claim 18, further comprising transmitting the output of thesensor to a computer for comparison to a stored predetermined wearprofile.